One of the indicators of climate change is the slow shift in the time of year at which plants flower, bud, leaf, drop their leaves, and disperse seeds. Such shifts have been seen in many locations worldwide.
To get a more extensive and consistent handle on the details in the US, a coalition of government agencies, universities, and scientific organizations has teamed up to expand a "citizen scientist" program that allows people all over the country to document the time at which local plants shift from one cycle to another.
"Project BudBurst"  launched its program for all 50 states on Feb. 15, 2008. Many people in your audience likely will want to participate in this effort, which drew thousands of responses for the pilot program last spring.